Purification of alkyl sulphates and resulting products



Patented July 16, 1940 t v y I t I UNITED STATES PATENT OFFlCE azowsa HPURIFICATION OF ALKYL SULPHATES AND RESULTING PRODUCTS Kenneth E. Long,South Euclid,,ji)hio,. assignor to The Harshaw Chemical Company, Elyria,Ohio, a corporation of Ohio No Drawing. Application August 24, 1938,

Serial No. 226,585

Claims. I (Cl. 260-459) This invention relates to the purification of hiy satisfactory f r use as an anti-pitting alkyl sulphates for use asantipitting agents in agent in the Watts type acid nickel plating bath.acid nickel plating. I have also found it to be compatible with otherTechnical sodium lauryl sulphate (sold under addition agents commonlyused in the Watts bath the trade-names, Duponol, Gardinol, Dreft, etc.)for produc ion of i h n such as r m tic 5 is an article of commerce andhas been used for sulphonates, selenious acid, zinc, etc. several yearsas an anti-pitting agent in aqueous, acid nickel plating solutions. Itis a sulphation product of a fraction of a fatty alcohol material A 5%aqueous 501111310 of a techmcal Sodlum derived from coconut. oil andcontains sodium lauryl Sulphate material, sold under the tradelaurylsulphate and higher and lower fatty alname DUPOHOI M. E. Dry, at atemperature of cohol sulphates between 8 and 18 carbon atoms F: was tedWith 60 grams per liter of as well as small quantities of free fattyalcohols H3BOB- The 30111171011 was Cooled and Example I and organicimpurities. I, fi e ed 001d. Some of the constituents of this material,the Ewample II 15 nature of which I do not know with certainty, A 5%aqueous Solution of Duponol E. Dry

but which appear as suspensoid or emulsoid imwas treated with 3 Ouncesper gallon f purities, are considered detrimental to the result-' 7 ingnickel plate, particularly in respect to salt N1SO4-6H2O sprayresistance. This has been known for some and filtered through activatedcharcoal. To the 20 time and workers in the art have attempted, butfiltrate, at 170 F., was added 50 grams per liter Without success. to pv a practical m o of r-neos. The solution was cooled to 50 F. and ofremoving the objectionable constituents. filtered cold.

I have discovered that if an aqueous solution Example 111 of technicalsodium lauryl sulphate, or the like material, is treated with boric acidand then cooled to a temperature low enough to produce a boric acidprecipitate, the undesirable constituents of the alcohol sulphatematerial separate out with the precipitate and are thus easily re moved,leaving a clear solution.

I find it desirable also to pretreat the sodium lauryl sulphate materialwith a suitablenickel salt, such as the sulphate or the chloride. Iprefer to add boric acid to the point of substantial saturation at anelevated temperature and then reduce the temperature whereby the boricacid is precipitated, forming in the solution a precipitate which eitherby chemical combination, adsorption, or otherwise carries down theundesirable constituents of the original material.

I can, for example, use a 1% to 10%, desirably a 5%, solution of sodiumlauryl sulphate and treat the same with from 25 to 100 grams per literof boric acid. The temperature at which 9 amd added Should below theduce a precipitate and removing the precipitate. bomng point of thesulta'bly to 3. Process of conditioning a technical material F. and thelowest temperature to which the solucomposed principally I of sodiumalkyl sulphates is reduced by refrigeration may be approxi' having from8 to 18 carbon atomsin the molecule mat ly th ezi p i t of t solution.desirfor use as an anti-pitting agent in acid nickel 50 ably 40 to F.Preferably theboric acid is plating, comprising providing an aqueoussolution added to substantial saturation at about to of said material ofa concentration from 1% to F. and the solution is then refrigerated to10% at a temperature not substantially below 40 to 60 F. and filteredcold. The filtrate is normal room temperature, adding boric acid and 55the desired product and I have found it to be refrigerating the solutionto a temperature suf- 55 A 5% aqueous solution of Duponol M. E. Dry, 25at a temperature of 70" F., was treated with 25 grams per liter ofHsBOs. The solution was cooled to 40 F. and filtered cold.

Having thus described my invention, what I claim is: 30

1. Process of conditioning a technical material composed principally ofsodium alkyl sulphates having from 8 to 18 carbon atoms in the moleculefor use as an anti-pitting agent in acid nickel plating, comprisingdissolving boric acid in an 35 aqueous solution thereof, cooling thesolution sufficiently to produce a precipitate, and removing theprecipitate.

g 2. Process of conditioning a technical material composed principallyof sodium alkyl sulphates 40 having from 8 to 18 carbon atoms in themolecule for use as an anti-pitting agent for acid nickel plating whichcomprises adding boric acid to an aqueous solution thereof tosubstantial saturation, refrigerating the resulting solution to pro-' 45ficiently low to cause boric acid to crystallize out.

4. Process of conditioning a technical material composed principally ofsodium alkyl sulphates having from 8 to 18 carbon atoms in the moleculefor use as an anti-pitting agent in acid nickel plating, comprisingproviding an aqueous solution of said material of a concentration from1% to 10% at a temperature not substantially below normal roomtemperature, adding boric acid and refrigerating the solution to atemperature sufficiently low to cause boric acid to crystallize out, andnot higher than 50 F.

5. As a new composition of matter an aqueous solution suitable for usein an acid nickel plating bath, free from suspended material and capableof enhancing the salt spray resistance of nickel deposits as compared totechnical sodium lauryl sulphate, containing such components oftechnical sodium lauryl sulphate as remain when a 1% to 10% aqueoussolution thereof is treated with from 25 to 100 grams per liter of boricacid at a temperature of from 70 F. to 100 Rand then cooled to atemperature of from 40 F. to 60 F. and filtered, said solution alsocontaining boric acid at least to the extent that the same is soluble insaid solution at 40 F.

KENNETH E. LONG.

